1. Field of the Invention
This invention relates to a three-dimensional image optical system that generates (presents) a three-dimensional optical image, specifically to an afocal three-dimensional image optical system to which an integral photography (IP) technology is applied.
2. Description of the Related Art
For one of the schemes for three-dimensional television that allows the three-dimensional vision from any of arbitrary viewing points, an IP (Integral Photography) three-dimensional camera device that uses a micro lens array apparatus or a pinhole array apparatus has been known. As one of applications of this IP three-dimensional system, a technology has been known wherein a radially graded refractive index rod lens (called a “radial GRIN lens”, hereinafter) which has a particular optical length (for example, a Japanese published patent application, H12-122191). The three-dimensional camera device according to this patent application uses optical fibers instead of the radial GRIN lenses, wherein the effective optical length of the fiber is set a half cycle or an odd cycle of the meridional serpentine period and the graded refractive index of the optical fiber has the characteristic of quadratic distribution to maintain a coherent guided mode of the optical wave traveling therein.
As for the apparatuses that use micro lens array optical devices, facsimiles and related image display devices, which convert the letters and symbols displayed on a plane into a spatial image via equi-magnification erecting optical system (for example, a Japanese patent application, H10-062717), are well known. This image display device has plural lens plates on which many micro lenses are aligned and color plates which have arrayed holes, each locating to each micro lens, therein and work as a means to create a uniform colored background.
The radial GRIN lenses have already been known and have been applied to specific technical fields by using the equivalent optical characteristics to convex lens systems (for example, the reference 3).
References
Ref. 1; Japanese patent application,2000-122191A
Ref. 2; Japanese patent application, H10-062717A
Ref. 3; Japanese patent application, H11-0305164A
However the three-dimensional image optical systems used for the conventional three-dimensional camera device have the following problems.
In the above first and the third references, the depth magnification is fixed to be a negative unity or a positive unity and no change of the magnification of the reproduced image is possible because the system is constructed in such a way that the subject image is reproduced through the transmission guide which has a fixed afocal characteristic. In addition, the conventional three-dimensional optical image cannot be reproduced close to or far from the elementary image optical subsystem that reproduces the three-dimensional optical image. As the result, the conventional technology has problems in terms of the fixed and non-adjustable depth magnification.
In the second reference as given in the above, it is not possible to create a three-dimensional image but only a planar image. Moreover, because a means to create a uniform colored background is additionally necessary in order to image a planar image, more optical components are required in order to complete a set of the apparatus. It is not possible to display the subject as it is as a result of having a means of uniform colored background. The additional means of the uniform colored background is not intended to reproduce the three-dimensional images and has a different system design from those to generate three-dimensional images.
There have been no appropriate conventional technologies of the optical apparatus to satisfy the requirements to be used for the application for the case when radiation materials or explosive materials are handled by remote controlled manipulators or magic handles in nuclear power plants or power factories and for requirements such that visitors are able to see the art works and exhibits in close view even when they are forced to be apart from the exhibiting subjects in the museums.
The present invention has been proposed to solve the issues seen in the above. The purpose of the present invention is to provide a new three-dimensional image optical system that allows adjustment of the position of the three-dimensional optical image reproduced without fixing for the depth magnification of the subjects and allows to visually observe the subjects in detail at the location apart from the subjects without using a means of uniform colored back ground.